WHO types A and AB thymomas: Not always benign

Rohit K. Jain, Rutika J. Mehta, John D. Henley, Kenneth A. Kesler, Patrick J. Loehrer, Sunil Badve

Research output: Contribution to journalArticle

29 Scopus citations


The 2004 WHO classification of thymic tumors recognizes five major subtypes of thymomas and thymic carcinoma. Subtypes A and AB thymomas are purported to be benign neoplasms, although prior studies have suggested a potential for malignant behavior. The purpose of this study was to assess the clinical behavior of A and AB thymomas identified from a large institutional pathologic database. A retrospective slide review of 500 thymic epithelial tumors identified 71 (14%) cases of types A and AB thymomas. Clinical history and follow-up information were obtained through retrospective chart review. There were 38 and 33 cases of types A and AB thymomas, respectively. Complete follow-up data were available in 37 (52%) cases. Eighteen (49%) patients (type A, n9 and type AB, n9) had evidence of recurrent/metastatic disease at an average of 62 months (range from 6 to 244 months) after initial diagnosis. Survival curves for patients with types A and AB thymomas, with and without recurrences, show a statistically significant difference (P=0.001 and 0.005, respectively). Analysis of this large cohort confirms the potential for subtypes A and AB thymomas to show malignant behavior. Long-term clinical monitoring, therefore, appears to be justified in these cases. This study also shows the poor correlation between the WHO classification and tumor behavior.

Original languageEnglish (US)
Pages (from-to)1641-1649
Number of pages9
JournalModern Pathology
Issue number12
StatePublished - Dec 1 2010


  • thymoma
  • type A
  • type AB
  • WHO

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

Fingerprint Dive into the research topics of 'WHO types A and AB thymomas: Not always benign'. Together they form a unique fingerprint.

  • Cite this